Search function of Files app in Iphone does not work.

Hi,

I have a problem with the Files app on my iPhone.

+ I searched for a file with the name, extension, and full name + extension. But nothing appears. "No results for... Check the spelling or try a new search."

+ In another case, I want to search in the current folder, but nothing appears although the files exist. And why does it search all of the files app, not a current folder?

Can you tell me why and how to resolve this? Thanks